This invention relates generally to decontamination systems, and more particularly, to apparatuses and methods for decontaminating in-situ groundwater by producing high amounts of dissolved oxygen and reactive initiators such as hydroxyl radicals.
Much attention has been given to the preservation of our water supplies and resources, particularly since the mid 1960""s. Agencies have become aware of the health effects of toxic pollutants on humans and the increased demands for potable water in this country and the world. Government agencies, for example, the Environmental Protection Agency (EPA), have responded by establishing maximum contaminant levels for many toxic chemical compounds. Today, once a chemical regulated under government law is identified in soil or water above the maximum contaminant level, facility operators or property owners are required to initiate assessment and remediation of the contamination. In some cases, the cost of cleaning up discharges of certain chemicals can greatly exceed the value of the contaminated property. In the past, the remediation of contaminated soil involved excavation and disposal of the impacted media. However, if the contaminant had reached the groundwater, the risk to the public welfare, remedial cost, and amount of time required to remove the contaminants increased substantially.
Biological treatment of water contaminants or organic chemicals with total petroleum hydrocarbons (TPH) and other contaminants has become an important process in controlling the pollution of the aquatic environment from industrial sources. The mineralization of organic chemicals depends on the nature of the chemical compounds involved. Some chemicals that find their way into the aquifer from industrial processes or natural processes resist degradation and are recalcitrant in nature; thereby accumulating in the environment.
It is well known that natural remediation occurs when facilitated by aerobic compounds in the soil. The injection of an oxygen release compound into the soil has been previously performed with a target of reducing the contaminants at a site. Some of these results are described in The ORC Oracle Newsletter 3:1, published by Regenesis.
This prior art method was a passive anaerobic biodegradation and was slow, incomplete and limited in its scope of impact. Since the system was passive, it was reliant on groundwater flow to distribute dissolved oxygen. Therefore, only groundwater downstream of the well was within the impacted area. Further, when the flow of groundwater was slow, the attenuation rate of the leached dissolved oxygen was correspondingly slow.
According to principles of the present invention, an apparatus is provided for increasing the quantity of dissolved oxygen in contaminated fluid. The apparatus includes a submersible pump for drawing the contaminated fluid across an electrolytic cell. The electrolytic cell includes a distribution chamber attached to an outlet of the cell. When the apparatus is immersed in the contaminated fluid and power is supplied to the pump and the cell, contaminated fluid enters through a pump intake, is pumped into a cell housing across the cell and exits out perforations in the distribution tube. Electricity flows through the fluid across charging plates of the cell, breaking some of the water molecules into their component parts of hydrogen gas and oxygen gas. At the outlet of the cell, both hydrogen gas and oxygen gas are present in the fluid. The distribution chamber is vertically oriented and longitudinally-extending from the outlet of the cell. The vertical length of the chamber is selected to provide a resident time for the fluid allowing a majority of the gaseous oxygen to transition to dissolved oxygen.
The apparatus can be used in-situ by placing the decontamination apparatus in a well below an elevation for the contaminated groundwater. When power is supplied to the system, the pump draws groundwater into the cell housing across the cell, while electricity flowing through the cell breaks some of the molecules into their component parts of hydrogen gas and oxygen gas. In some embodiments, it also generates reactive initiators to further remediate the contaminated groundwater.